Bipolar electrode structure for monitoring fetal heartbeat and the like

ABSTRACT

An improved electrode system for monitoring fetal heartbeat includes a curved guide tube adapted to be inserted through the vagina and cervix of a woman in labor, a retaining coil mounted on a holder member which is slidably disposed in the guide tube, a flexible driving tube adapted to rotate the holder member to screw the retaining coil into a fetal epidermis and two spaced electrodes which are adapted to be electrically connected to a suitable apparatus for monitoring fetal heartbeat. In the first disclosed embodiment of the invention one of the electrodes is a pointed member mounted in the holder which mounts the retaining coil. The retaining coil, when screwed into the fetal epidermis, maintains the pointed first electrode in piercing engagement with the fetus. In the second disclosed embodiment the retaining coil and the first electrode are one and the same structure, i.e., the first electrode is in the form of a coil which is adapted to screw into the fetal epidermis. In both of the embodiments disclosed the second electrode is spaced from the first electrode and electrical contact between the two electrodes is established by vaginal and cervical secretions of the woman in labor. Driving connection between the holder member and the flexible driving tube is provided by slots in the forward end of the driving tube and fin means on the holder. In the second embodiment disclosed the second electrode is in the form of a flat member mounted on the rear end of the holder and serves as the fin means.

This applicaton is a continuaton-in-part of U.S. Pat. application Ser.No. 108,034, filed Jan. 20, 1971.Iadd., now abandoned.Iaddend..

The present invention relates to an improved bipolar electrode structureadapted to be inserted through the vagina and cervix of a woman inlabor, into contact with the fetus. The electrode structure is designedto be operatively connected to an amplifier and a cardiotachometer forrecording the fetal electrocardiogram and heart rate during labor anddelivery.

It has long been recognized that monitoring fetal heartbeat is a mostimportant procedure during the conduct of labor. Various types ofmethods and apparatuses for performing this monitoring function havebeen designed in recent years. The most successful and practicaltechniques are those employing electrodes which are attached to thefetus.

One such technique is described in Volume 35, No. 1, of Obstetrics andGynecology, January 1970 issue, pages 111-113. The technique theredescribed utilizes a vaginal endoscope and specially designed forceps toapply a silver electrode to the fetal scalp.

A second type of electrode structure for recording fetal heartbeat isdescribed in Volume 16, No. 5 of Obstetrics and Gynecology, November1960 edition, pages 567-570, The electrode structure there described isa unipolar structure comprising a spring steel clip adapted to be closedby a sliding plastic sleeve to engage the fetal scalp or buttocks.

The foregoing electrode structures give rise to several problems whichthe structure of the present invention is designed to overcome. Both the"forceps-endoscope" and the "sliding sleeve-clip" types of electrodescannot be applied until the mother's cervix has dilated to about 2.0 cm,and thus cannot ordinarily be applied during the very early stages oflabor.

Another disadvantage associated with the foregoing types of electrodesis that both include clips which must be squeezed onto the fetalepidermis. These clips are extremely thin and brittle and are oftencracked or damaged by mechanical stresses during application. Suchcracks create electrical "noise" in the electrocardiogram system duringthe fetal heartbeat monitoring operation, and thus interfere with suchmonitoring studies.

The foregoing types of electrodes are also relatively difficult to applyand remove. The "forceps-endoscope" system reqires a specially designedlighting apparatus which must be used to insure proper application ofthe electrode.

In view of the foregoing, it is an object of the present invention toprovide a vaginal electrode structure which overcomes the foregoingproblems associated with the prior art electrode structures.

A further object of the present invention is to provide an improved,durable, vaginal electrode structure which can be quickly andeffectively applied to the fetus during a relatively early stage oflabor, and which can be quickly and easily removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side elevational view of the forward portion of afirst preferred embodiment of the electrode structure of the presentinvention, with the various parts thereof positioned as they would beprior to use.

FIG. 2 is a perspective view of the holder member, first electrode,retaining coil and the forward end of the driving tube of the electrodestructure shown in FIG. 1.

FIG. 3 is a sectional side elevational view of the rear portion of theelectrode structure shown in FIGS. 1 and 2.

FIG. 4 is a sectional side elevational view showing the electrodestructure of FIGS. 1-3 with a modified form of the second electrode.

FIGS. 5, 6 and 7 are diagrammatic views illustrating the manner in whichthe improved electrode structure of the present invention is applied toa fetus.

FIG. 8 is a perspective view of a second preferred embodiment of anelectrode structure constructed according to the teachings of thepresent invention, wherein the retaining coil serves as the firstelectrode and wherein the first and second electrodes are mounted on thesame holder.

FIG. 9 is a sectional side elevational view of the electrode structureshown in FIG. 8 with the various parts thereof positioned as they wouldbe prior to use.

FIG. 10 is a side elevational view, partly in section, showing theelectrode unit rotated 90 degrees from the position illustrated in FIG.9.

DESCRIPTION OF EMBODIMENT OF FIGS. 1-7

Referring now to the drawings, the electrode structure 10 illustrated inFIGS. 1, 2 and 3 comprises a guide tube 12 having an open forward endthrough which a holding member 14 is movable, and an open rear endthrough which electrode wires 16, 18 extend. The guide tube 12 is curved.Iadd.and form-sustaining .Iaddend.(see FIGS. 5-7) to facilitateinsertion of the tube through the vagina and cervix of a woman in labor.

One of the wires 16 extends through the holding member 14 and iselectrically connected to a pointed electrode 20 which is preferablymade of silver-silver chloride. The desirability of using asilver-silver chloride electrode is discussed in some detail in Volume30, No. 2 of Obstetrics & Gynecology, August 1967 issue, pages 281-286.The electrode 20 is preferably crimped on the forward end of wire 16, asat 22 (FIG. 1) and soldered thereto to insure a good electricalconnection.

An insulating sleeve 24 covers the juncture of the first wire 16 and thefirst electrode 20. Epoxy adhesive 26 fills and seals the annular spacebetween the insulation 17 of wire 16 and the interior wall of the holder14, behind the sleeve 24. The epoxy 26 also covers and seals the rearend of the holder 14.

Epoxy adhesive is also provided in the annular space 28 between theelectrode 20 and the interior wall of tube 24, in the annular space 30between the wire 16 and the interior wall of the tube 24, in the annularspace between the wire insulation 17 and the interior wall of tube 24,and in the annular space 36 between the exterior wall of tube 24 and theinterior wall of the holder 14. The epoxy adhesive at these locationsinsures a good seal from the forward end of the holder 14.

The forward end 40 of the holder 14 has a retaining coil 42 mountedthereon by means of a suitable adhesive 44 (e.g., epoxy). The retainingcoil 42 (which may be plastic, metal or any other suitable material) isprovided with a pointed forward end 46 to pierce the fetal epidermis.When the holding member 14 and the retaining coil 42 are rotated theretaining coil will "screw" into the fetus and bring the first electrode20 into engagement with the fetal epidermis with the pointed tip 47piercing the epidermis. The forward end 40 of the holder 14 acts as a"stopper" which limits the distance which the tip 47 of the firstelectrode 20 can travel into the fetus. The distance between the pointedend 46 of the retaining coil 42 and the forward end 40 of the holdermember 14 is relatively small (e.g., about 1/16 of an inch).

As best shown in FIG. 2, the rear portion 49 of the holder member 14 isprovided with a plurality of radially outwardly extending,circumferentialy spaced wings of fins 50,50,50,50, which are adapted tobe releasably engaged by circumferentially spaced slots 52,52,52,52, inthe forward end 53 of a flexible driving tube 54. .Iadd.The guide tube12 is more rigid than the flexible driving tube 54 so that the guidetube will maintain its curved configuration when the flexible drivingtube is rotated within it. .Iaddend.

The flexible driving tube 54 (preferably made of plastic) extendsthrough the curved guide tube 12 for rotating the holder 14 and theretaining coil 42. As noted above, rotation of the holder 14 by theflexible driving tube 54 is accomplished via the slots 52 in the forwardend 53 of the driving tube and the fins 50 on the holder. It should benoted that the driving connection between the fins 50 and the slots 52is relatively "loose" so that the driving tube 54 will "slip" around theholder fins 50 when the holder meets with a relatively slight amount ofresistance to rotation. Thus, when the holder 14 meets with resistanceto rotation (e.g., when the first electrode 20 has pierced the fetalepidermis and the forward end of the holder has come into contact withthe fetus), continued rotation of the driving tube 54 will not drive theretaining coil or first electrode further into the fetus. This "loosedriving connection" may be accomplished by making the fins 54 or thedriving tube segments 56 between the slots 52 "soft" or pliable enoughso that they will bend and "slip" relative to one another when theholder 14 resists rotation.

Referring to FIG. 1, it will be seen that the forward end of the secondconductor 18 terminates within the guide tube 12 substantially behindthe holder 14. A silver-silver chloride electrode coil 60 is crimped (asat 62, FIG. 1) and soldered onto the forward end of the second conductor18. The coil .[.20.]. .Iadd.60 .Iaddend.is the second electrode in thesystem and also functions to hold the conductors 16, 18 adjacent to oneanother.

A plastic insulating sleeve 64 is provided around the juncture of theelectrode coil 60 and the second conductor 18 to eliminate or minimizeany electrical noise which otherwise might be created if the juncture ofthe conductor 18 and the electrode coil 60 were exposed to vaginalfluids when the system is in use.

Epoxy adhesive is preferably provided between the interior wall of theinsulating sleeve 64 and the rear end of the coil electrode 60 to sealthe forward end of the insulating sleeve. Epoxy adhesive is alsopreferably provided between the conductor 18 and the interior wall ofthe insulating sleeve 64 (as at 66, FIG. 1), and between the interiorwall of the insulating sleeve 64 and the insulation cover 19 on thesecond conductor 18 to seal these junctures.

In FIG. 4, an alternative structure for the second electrode is shown.In the FIG. 4 embodiment the second electrode 160 is in the form of asleeve which is crimped and soldered onto the forward end of the secondconductor 18 and an insulating sleeve 164 encloses both of theconductors 16, 18. Epoxy adhesive is preferably provided in the FIG. 4structure to seal the juncture between the electrode sleeve 160 and theconductor 18 from vaginal fluids.

As best shown in FIG. 1, the electrode structure 10 of the presentinvention is packaged so that the retaining coil 42 and the firstelectrode 20 are well behind the forward end of the guide tube 12,thereby protecting the retaining coil and electrode from damage prior touse.

As best shown in FIG. 5, the rear ends of the wires 16, 18 are foldedback and inserted between the rear end of the curved guide tube 12 andthe rear portion of the flexible driving tube 54. A wedge 80 (FIGS. 5and 7) may be inserted in the rear end of the driving tube 54 to.[.prevent relative sliding movement between the flexible driving tubeand the wires 16, 18..]. .Iadd.wedge the wires 16 and 18 against theinterior surface of the driving tube 54. Since wire 16 is secured to theholder 14, if the wires are pulled, the fins 50 are urged toward slots52 of the driving tube. Accordingly, if the wires 16 and 18 are heldwith the fins 50 engaging slots 52 of the driving tube, the wires thenaid in locking the holder and driving tube together during insertion ofthe electrode. .Iaddend.

The method of using the electrode structure 10 of the present inventionis illustrated diagrammatically in FIGS. 5, 6 and 7.

With the first and second electrodes, 20 and 60, disposed within theguide tube 12, the doctor inserts the forward end of the curved guidetube through the mother's vagina 82 and cervix 84 until the forward endof the guide tube makes contact with the fetal head 86 (or other portionof the fetus), as shown in FIG. 5. The doctor then removes thefolded-back ends of the wires 16, 18 from between the rear ends of theguide tube 12 and the driving tube 54 to permit relative slidingmovement between these tubes. While holding the forward end of the guidetube 12 stationary, the doctor then pushes the rear end of the flexibledriving tube 54 forwardly until the retaining coil 42 makes contact withthe fetal epidermis (FIG. 6). An indicator mark 88 (FIGS. 5-7) may beprovided on the driving tube 54 to visually warn the doctor when theretaining coil 42 has passed beyond the forward end of the guide tube12.

When the doctor feels or sees that the retaining coil 42 has contactedthe fetal epidermis 86, he rotates the flexible driving tube 54 (e.g.,about one full turn) while maintaining the forward end of the guide tube12 against the fetal head. This will screw the retaining coil 42 intothe fetal epidermis and drive the pointed end of the first electrode 20into the epidermis (see FIG. 6). It will be appreciated that theflexible construction of the driving tube 54 permits it to slide androtate in the curved guide tube 12.

The wedge 80 is then removed from the rear end of the driving tube 54 to.[.permit relative sliding movement between the wires 16, 18 and.]..Iadd.release wires 16 and 18 with respect to driving tube 54 andthereby permit disengagement of the interlocking fins 50 and slots 52 bywithdrawal of .Iaddend.the driving tube. The doctor then removes hisfingers from the mother's vagina 82, grasps the outer ends of thedriving tube and the guide tube, and slides these tubes (as a unit) offof the wires 16, 18 leaving only the electrodes 20 and 60, and the verythin wires 16, 18 within the mother.

The outer ends of the wires 16, 18 are then connected to suitableapparatus (not shown) for monitoring fetal heartbeat.

DESCRIPTION OF THE EMBODIMENT OF FIGS. 8-10

FIGS. 8-10 illustrate a second preferred embodiment of the electrodestructure of the present invention wherein the first electrode serves asthe retaining coil and the second electrode is mounted on the holdermember and serves as the fin means which cooperates with the slots inthe forward end of the flexible driving tube to provide the drivingconnection between the holder and the driving tube.

Referring to FIG. 9, the electrode structure 210 comprises a curved.Iadd., form-sustaining .Iaddend.guide tube 212 having an open forwardend through which a holder member 214 is adapted to pass. The holdermember 214 has a spiral electrode 220 mounted in its forward end and agenerally flat electrode 222 mounted in its rear end. .Iadd.

As shown in FIG. 9, the diameter of the cylindrical holder member 214approximates the inner diameter of guide tube 212. Consequently, theholder member prevents lateral movement of the electrode coil 220(relative to the guide tube) while the coil is being attached to thefetus. Moreover, the length of the holder member 214 is such that whenthe spiral electrode 220 extends just beyond the end of the guide tube212 (for attachment to the fetus), the cylindrical holder member withinthe guide tube prevents skewing of the coil. These features help toreduce the possibility of injury to the fetus when the electrode isbeing applied. .Iaddend.

A first electrode wire 216 extends through the rear end of the holdermember 214 and is electrically connected to the rear end of spiralelectrode 220. A second electrode wire 218 also extends through the rearend of holder member 214 and is electrically connected to the forwardend of the second electrode 222.

Both electrodes, 220 and 222, are preferably constructed of stainlesssteel and are soldered to their respective electrode wires, 216 and 218.The holder member 214 is made of an insulative material, such asplastic, and electrically isolates the electrodes 220 and 222 from oneanother.

A flexible driving tube 254 is slidably and rotatably disposed in thecurved guide tube 212 for rotating the holder 214 to screw the spiralelectrode 220 into a fetal epidermis. As best shown in FIG. 8, theforward end of the driving tube 254 is provided with a pair of slots252, 252 which are adapted to receive the rearwardly extending portionof the plate electrode 222. When the slots 252, 252 on the forward endof the holder 214 engage the plate electrode 222 the holder 214 and thespiral electrode 220 may be rotated by rotating the flexible drivingtube 254.

The electrode wires, 216 and 218, extend rearwardly through the rearportion (not shown) of the driving tube 254 and the rear portion (notshown) of the guide tube 212 for connection to a suitable apparatus (notshown) for monitoring fetal heartbeat.

The electrode structure 210 is used in the same manner as describedabove and illustrated in FIGS. 5-7 in connection with the structure ofFIGS. 1-7. In use, with the spiral electrode 220, holder 214 and plateelectrode 222 disposed within the curved guide tube 212, behind theforward end thereof, the doctor inserts the forward end of the guidetube 212 through the woman's vagina and cervix until the forward end ofthe guide tube makes contact with the fetal head (or other portion ofthe fetus) in the same manner as described above in connection with theelectrode structure 10 illustrated in FIGS. 1-7. The doctor then holdsthe forward end of the guide tube 212 stationary and pushes the rear endof the flexible driving tube 254 forwardly until the spiral electrode220 makes contact with the fetal epidermis.

When the doctor feels or sees that the spiral electrode 220 hascontacted the fetal epidermis, he rotates the flexible driving tube 254while maintaining the guide tube 212 against the fetal head to screw thespiral electrode 220 into the fetal epidermis.

It is intended that the present invention be limited only by the scopeof the appended claims.

We claim:
 1. An apparatus for use in monitoring fetal heartbeat and thelike comprising:a .[.relatively rigid.]. .Iadd.form-sustaining.Iaddend.,curved guide tube adapted to be inserted through the vagina and cervixof a woman in labor; a holder member slidably and rotatably disposed insaid guide tube; a retaining coil mounted on said holder member andadapted to be screwed into a fetal epidermis by rotating the holdermember; monitoring means mounted on said holder member; a flexible drivetube slidably and rotatably disposed in said curved guide tube formoving said holder member through said guide tube to bring saidretaining coil into engagement with a fetal epidermis and for rotatingsaid holder member to screw said retaining coil into the epidermis;.[.and.]. .Iadd.said guide tube being more rigid than said drive tube sothat said guide tube will maintain its curved configuration when saidflexible drive tube is rotated within it; and .Iaddend. cooperatingmeans on said drive tube and said holder member for rotating said holdermember and said retaining coil by rotating said drive tube.
 2. Theapparatus according to claim 1, wherein said retaining coil comprises afirst electrode.
 3. The apparatus according to claim 2, and furthercomprising a second electrode mounted on said holder member and spacedfrom said first electrode; said holder member comprising insulatingmaterial.
 4. The apparatus according to claim 1, and further comprisinga first electrode mounted on said holder member and adapted to contactthe epidermis into which the said retaining coil is screwed.
 5. Theapparatus according to claim 1, wherein said drive tube has asubstantially uniform outer diameter throughout the length thereof, andsaid guide tube has a substantially uniform inside diameter throughoutthe length thereof; the outer diameter of said drive tube being smallerthan the inside diameter of said guide tube, whereby said drive tube maybe freely slid forwardly and rearwardly in said guide tube.
 6. Animproved electrode structure for monitoring fetal heartbeat and the likecomprising:an elongated, .[.relatively flexible, rigid.]..Iadd.form-sustaining.Iaddend., relatively narrow guide tube having anopen forward end adapted to be inserted through the vagina and cervix ofa woman in labor; a generally cylindrical holder member slidably androtatably disposed within said guide tube; said holder member having aforward end portion and a rear end portion; a plurality ofcircumferentially-spaced driving fins on the rear end portion of saidholder member; a retaining coil mounted on the forward end portion ofsaid holder member; said retaining coil terminating in a pointed forwardend spaced forwardly of the forward end of said holder member; a firstelectrode mounted in said holder member; said first electrode includinga rear portion mounted in said holder member, and a pointed forward endextending through the forward end of said holder member; said pointedforward end of said first electrode terminating rearwardly of thepointed forward end of said retaining coil; a first electrical wireconductor having a forward end extending through the rear end of saidholder member and electrically connected to said first electrode;insulating means covering the juncture of said first electrode and saidfirst electrical wire conductor; an elongated, relatively flexibledriving tube slidably and rotatably disposed in said guide tube; saiddriving tube having a forward end provided with a plurality ofaxially-extending, circumferentially-spaced driving slots releasablyengaging said driving fins on said holder member for rotating saidholder member when said driving tube is rotated; .Iadd. said guide tubebeing more rigid than said driving tube so that said guide tube willmaintain its curved configuration when said flexible driving tube isrotated within it; .Iaddend. a second electrode slidably disposed withinsaid driving tube, rearwardly of said slotted forward end thereof; asecond electrical wire conductor having a forward end electricallyconnected to said second electrode; insulation means covering thejuncture of said second electrical wire conductor and said secondelectrode; said first and second electrical wire conductors having rearends extending out of the rear ends of said driving tube and said guidetube for connection to an electrical monitoring apparatus.
 7. Animproved electrode structure according to claim 6, wherein said drivingtube is longer than said guide tube, and has a rear end portionextending rearwardly of the .[.reare.]. .Iadd.rear .Iaddend.end of saidguide and further comprising an indicator mark on said rear end portionof said driving tube for indicating to the user when the pointed forwardend of said retaining coil approaches the forward end of said guidetube.
 8. An improved electrode structure according to claim 6, whereinsaid second electrode is formed in the shape of a coil .[.,.].encircling said first electrical wire to hold said first and secondelectrical wires adjacent one another.
 9. An improved electrodestructure according to claim 6, wherein said first electrode is made ofa silver-silver chloride composition.
 10. An improved electrodestructure according to claim 6, wherein said second electrode is formedin the shape of a tubular sleeve.
 11. An improved electrode structurefor use in monitoring fetal heartbeat and the like comprising:a.[.relatively rigid.]. .Iadd.form-sustaining.Iaddend., curved elongatedguide tube having an open forward end adapted to be inserted through thevagina and cervix of a woman in labor; holder means slidably androtatably disposed in said guide tube; a retaining coil connected tosaid holder means and adapted to engage a fetal epidermis; a flexibledriving tube slidably and rotatably disposed in said guide tube fordriving said retaining means into engagement with a fetal epidermis;said .[.drive.]. .Iadd.driving .Iaddend.tube having a forward end; andmeans on said forward end of said driving tube operatively connected tosaid retaining coil for rotating said retaining coil to screw said coilinto the fetal epidermis; .Iadd. said guide tube being more rigid thansaid driving tube so that said guide tube will maintain its curvedconfiguration when said flexible driving tube is rotated within it;.Iaddend. an electrode mounted on said holder means; and means forelectrically connecting said electrode to an electrical monitoringapparatus.
 12. An improved electrode structure according to claim 11,wherein said electrode comprises a pointed electrode spaced from saidretaining coil, and wherein said retaining coil is adapted to maintainsaid pointed electrode in engagement with the fetal epidermis when saidretaining coil is screwed into the fetal epidermis.
 13. An improvedelectrode structure according to claim 11, wherein said electrodeincludes at least a portion of said retaining coil.
 14. An improvedelectrode structure according to claim 11, wherein said electrodecomprises a silver-silver chloride electrode.
 15. An improved electrodestructure according to claim 11, wherein said retaining coil is mountedon one end of said holder member; fin means on the other end of saidholder member; and wherein said means on said forward end of saiddriving tube comprises a plurality of slots releasably engaging said finmeans on said holder member for rotating said holder member and saidretaining coil when said driving tube is rotated.
 16. An improvedelectrode structure according to claim 11, and further comprising asecond electrode disposed in said guide tube rearwardly of said firstelectrode, and means for electrically connecting said second electrodeto an electrical monitoring apparatus.
 17. An improved structure for usein monitoring fetal heartbeat and the like comprising:a .[.relativelyrigid.]. .Iadd.form-sustaining.Iaddend., elongated, curved guide tubehaving an open forward end adapted to be inserted through the vagina andcervix of a woman in labor; a holder member slidably and rotatablydisposed within said guide tube; said holder member having a forward endportion and a rear end portion; a retaining coil mounted on the forwardend portion of said holder member; said retaining coil terminating in apointed forward end spaced forwardly of the forward end of said holdermember; electrode means mounted on said holder member; an elongated,relatively flexible driving tube slidably and rotatably disposed in saidguide tube; .[.and.]. .Iadd. said guide tube being more rigid than saiddriving tube so that said guide tube will maintain its curvedconfiguration when said flexible driving tube is rotated within it; and.Iaddend. cooperating engaging means on said rear end portion of saidholder member and the forward end portion of said driving tube forrotating said holder member and said retaining coil by rotating saiddriving tube.
 18. An apparatus for monitoring fetal heartbeat and thelike comprising:a .[.relatively rigid.]. .Iadd.form-sustaining.Iaddend.guide tube having an open forward end; said guide tube beingcurved to conform to and fit the angular anatomical configuration of awoman's vagina and cervix so as to be adapted to be comfortably insertedthrough the vagina and cervix of a woman in labor; a holder memberadapted to be slidably and rotatably disposed in said guide tube; saidholder member having a forward end and a rear end; an electrode coilmounted on said forward end of said holder member and being adapted tobe screwed into an epidermis when said holder member is rotated; saidelectrode coil having a pointed forward end adapted to pierce anepidermis; a flexible driving tube adapted to be slidably and rotatablydisposed in said curved guide tube for selectively moving and rotatingsaid holder member and said electrode coil; said driving tube having aforward end; .Iadd. said guide tube being more rigid than said drivingtube so that said guide tube will maintain its curved configuration whensaid flexible driving tube is rotated within it; .Iaddend. cooperatingdrive means on said driving tube and on said holder member for rotatingsaid holder member and said electrode coil when said driving tube isrotated; and means for electrically connecting said electrode coil to anelectrical monitoring apparatus.
 19. The apparatus according to claim 18and further comprising a second electrode mounted on said rear end ofsaid holder member and spaced from said first electrode; said holdermember comprising insulating material electrically insulating said firstand second electrodes from one another.
 20. The apparatus according toclaim 19, wherein said second electrode comprises a generally flatmember, and wherein said cooperating drive means comprises slots in theforward end of said driving tube and a portion of said flat secondelectrode.
 21. An improved structure for use in monitoring fetalheartbeat and the like comprising:a .[.relatively rigid.]..Iadd.form-sustaining.Iaddend., elongated guide tube having an openforward .Iadd.end.Iaddend.; said guide tube being curved to conform toand fit the angular anatomical configuration of a woman's vagina andcervix so as to be adapted to be confortably inserted through the vaginaand cervix of a woman in labor; a holder member slidably and rotatablydisposed within said guide tube; said holder member having a forward endportion and a rear end portion; a retaining coil mounted on the forwardend portion of said holder member; said retaining coil terminating in apointed forward end spaced forwardly of the forward end of said holdermember; monitoring means mounted on said holder member; an elongated,relatively flexible driving tube slidably and rotatably disposed in saidguide tube; .[.and.]. .Iadd. said guide tube being more rigid than saiddriving tube so that said guide tube will maintain its curvedconfiguration when said flexible driving tube is rotated within it; and.Iaddend. cooperating engaging means on said rear end portion of saidholder member and the forward end portion of said driving tube forrotating said holder member and said retaining coil by rotating saiddriving tube; said cooperating engaging means on said rear end portionof said holder member and on the forward end portion of said drivingtube establishing a relatively loose connection so that the engagingmeans on the forward end of said driving tube will slip around saidengaging means on the rear end portion of said holder member when theholder member meets with a predetermined amount of resistance torotation.
 22. An improved structure according to claim 21, wherein saidcooperating engaging means on said rear end of said holder member andthe forward end of said driving tube comprise fin means on one of saidholder member or said driving tube and slots in the other of said holdermember or said driving tube.
 23. An improved structure for use inmonitoring fetal heartbeat and the like comprising:a .[.relativelyrigid.]. .Iadd.form-sustaining.Iaddend., elongated guide tube having anopen forward .Iadd.end.Iaddend., said guide tube being curved to conformto and fit the angular anatomical configuration of a woman's vagina andcervix so as to be adapted to be comfortably inserted through the vaginaand the cervix of a woman in labor; a holder member slidably androtatably disposed within said guide tube; said holder member having aforward end portion and a rear end portion; a retaining coil mounted onthe forward end portion of said holder member; said retaining coilterminating in a pointed forward end spaced forwardly of the forward endof said holder member; monitoring means mounted on said holder member;an elongated, relatively flexible driving tube slidably and rotatablydisposed in said guide tube; .[.and.]..Iadd. said guide tube being morerigid than said driving tube so that said guide tube will maintain itscurved configuration when said flexible driving tube is rotated withinit; and .Iaddend. fin means on said rear end of said holder member andmeans defining slots in the forward end of said driving tube forreleasably engaging said fin means and rotating said holder member andsaid retaining coil by rotating said driving tube; the portions of theforward end of said driving tube between said slots being relativelysoft and flexible to establish a relatively loose connection with saidfin means so that the forward end of said driving tube will slip aroundsaid fin means on the rear end portion of said holder member when theholder member meets with a predetermined amount of resistance torotation.
 24. An apparatus for use in monitoring fetal heartbeat and thelike comprising:a holder member; a retaining coil mounted on said holdermember and adapted to be screwed into a fetal epidermis by rotating theholder member; monitoring means mounted on said holder member; anelongated tube for moving said holder member to bring said retainingcoil into engagement with a fetal epidermis and for rotating said holdermember to screw said retaining coil into the epidermis; and slots in theforward end of said tube and fin means on said holder member, wherebysaid holder member and said retaining coil may be rotated by rotatingsaid tube.
 25. An improved electrode structure for use in monitoringfetal heartbeat and the like comprising:holder means having fin meansthereon; a retaining coil connected to said holder means and adapted toengage a fetal epidermis; a driving tube for driving said retainingmeans into engagement with a fetal epidermis; said drive tube having aforward end; and slots in said forward end of said driving tubeoperatively connected to said fin means on said holder means forrotating said holder means and said retaining coil to screw said coilinto a fetal epidermis; an electrode mounted on said holder means; andmeans for electrically connecting said electrode to an electricalmonitoring apparatus.
 26. An improved structure for use in monitoringfetal heartbeat and the like comprising:a .[.relatively rigid.]..Iadd.form-sustaining.Iaddend. , elongated outer tube having an openforward end adapted to be inserted through the vagina and cervix of awoman in labor; a holder member slidably and rotatably disposed withinsaid outer tube; said holder member having a forward end portion and arear end portion; a retaining coil mounted on the forward end portion ofsaid holder member; said retaining coil terminating in a pointed forwardend spaced forwardly of the forward end of said holder member;monitoring means mounted on said holder member; an elongated drivingtube disposed in said outer tube; .[.and.]. .Iadd. said guide tube beingmore rigid than said driving tube so that said guide tube will maintainits curved configuration when said flexible driving tube is rotatedwithin it; and .Iaddend. fin means on said holder member and slots inthe forward end portion of said driving tube for rotating said holdermember and said retaining coil by rotating said driving tube. .Iadd. 27.A fetal electrode structure for use in monitoring fetal heartbeat,comprising: an elongated, cylindrical, form-sustaining guide tube curvedto conform to and fit the angular anatomical configuration of a woman'svagina and cervix so as to be comfortably inserted through the vaginaand cervix of a woman in labor, said guide tube having a forward end anda rear end and being adapted to maintain its curved configuration when aflexible driving tube is rotated within it; a cylindrical holderslidably and rotatably disposed in said guide tube, said holder beingmade of an electrically insulating material and having a forward endsurface and a rear end surface, the length and diameter of the holderbeing such as to prevent substantial lateral movement and skewing ofsaid holder relative to said guide tube when the forward portion of saidholder extends from said guide tube; an electrode coil extending fromthe front end surface of said cylindrical holder and terminating in aforward, pointed end adapted to pierce a fetal epidermal layer; a secondelectrode extending rearwardly from the rear end surface of saidcylindrical holder, said second electrode being electrically insulatedfrom said electrode coil; a flexible driving tube slidably and rotatablydisposed in said guide tube, said driving tube having a forward end anda rear end, said guide tube being more rigid than said driving tube;first and second wires passing through said driving tube into the rearend surface of said holder and electrically contacting said electrodecoil and second electrode, respectively, said wires extending from therear end of said driving tube; cooperating engaging means on the rearend surface of said holder and the forward end of said driving tube forreleasably connecting said driving tube and said holder for rotatingsaid holder about its axis within said guide tube.
 28. A fetal electrodestructure according to claim 27, further comprising means forselectively holding said wires at the rear end of said driving tube forlocking said cooperating engaging means together.
 29. A fetal electrodestructure according to claim 27, wherein said cooperating engaging meanscomprises said second electrode and slots in the forward end of saiddriving tube for engaging said second electrode.
 30. A fetal electrodestructure according to claim 29, wherein said second electrode comprisesa flat plate.
 31. A fetal electrode structure according to claim 27,wherein said second electrode comprises a flat metal plate.
 32. A fetalelectrode structure according to claim 30, further comprising means forselectively holding said wires at the rear end of said driving tube forlocking said cooperating engaging means together.
 33. A fetal electrodestructure according to claim 27, including means on said driving tubefor indicating when said electrode coil extends a preselected distancebeyond the forward end of said guide tube.
 34. A fetal electrodestructure according to claim 27, wherein the outer diameter of saiddriving tube is less than the diameter of said holder. A fetal electrodestructure for use in monitoring fetal heartbeat, comprising:aform-sustaining, elongated cylindrical guide tube curved to conform toand fit the angular anatomical configuration of a woman's vagina andcervix so as to be comfortably inserted through the vagina and cervix ofa woman in labor, having a forward end and a rear end; a cylindricalholder having a front face and a rear face, the cylindrical surface ofsaid holder engaging the inner surface of said guide tube for enablingslidable movement and rotation of said holder within said guide tube; anelectrode coil extending from the front face of said cylindrical holderand terminating in a forward, pointed end adapted to pierce a fetalepidermal layer; a flat electrode fin perpendicular to the rear face ofsaid cylindrical holder, said electrode fin substantially located on adiameter of said rear face and being electrically insulated from saidelectrode coil; a relatively flexible driving tube slidably androtatably disposed in said guide tube, said driving tube having aforward end and a rear end; said guide tube being more rigid than saiddriving tube so that said guide tube will maintain its curvedconfiguration when said flexible driving tube is rotated within it;first and second wires passing through said driving tube into the rearface of said holder and electrically contacting said electrode coil andflat electrode fin, respectively, said wires extending rearwardly fromthe rear end of said driving tube; slots in the forward end of saiddriving tube for releasably engaging said electrode fin; and means forselectively holding said wires at the rear end of said driving tube forlocking said slots and flat electrode fin together.
 36. A fetalelectrode structure according to claim 35, wherein said driving tubeincludes arcuate drive segments between said slots, said arcuate drivesegments being sufficiently pliable to slip over said electrode fin whenthe rotational drive force transmitted from said driving tube to saidholder exceeds a predetermined limit..Iaddend.